Portable power bank



FIG. 1 is a perspective view of a portable power bank showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof; and,

FIG. 8 is a perspective view of the portable power bank of FIG. 1 with an electronic device connected thereto.

The broken lines of the figures are for the purpose of illustrating environment and form no part of the claimed design. 

The ornamental design for a portable power bank, as shown and described. 